Laser scanners that scan laser light toward a target object are known (e.g., see Patent Literature (PTL) 1). Such laser scanners can measure the distance between the laser scanner and the target object by, for example, detecting laser light reflected back from the target object.
The conventional laser scanner according to PTL 1 includes, disposed along the optical axis of the laser light emitted from the light source, a mirror with an aperture and a scanning mirror. The mirror with the aperture is disposed between the light source and the scanning mirror. The aperture of this mirror is formed to allow the laser light emitted from the light source to pass through the mirror. A reflective surface is formed on the mirror with the aperture, on the side facing the scanning mirror. The scanning mirror, in contrast, scans the laser light emitted from the light source toward a target object, and oscillates about a predetermined axis.
The laser light emitted from the light source is reflected by the scanning mirror after passing through the mirror with the aperture. The oscillation of the scanning mirror scans the reflected laser light toward the target object. The laser light reflected from the target object is reflected by the scanning mirror, and then reflected by the reflective surface of the mirror with the aperture. The laser light is reflected from the reflective surface of the mirror with the aperture, condensed after passing through a condenser lens, and then received (detected) by a photodetector.